Giannis Antetokounmpo's X-ray on his lower back contusion came up clear but Milwaukee Bucks head coach Mike Budenholzer said they will monitor him ahead of Game 2.

Antetokounmpo exited Sunday's 130-117 loss to the Miami Heat in Game 1 of their first-round playoff series after landing heavily on his back with 4:13 left in the first quarter.

The Greek forward was slow to get back up and attempted to play through the issue, but was hobbled and re-exited with 9:56 left in the second quarter, with the Bucks proceeding to rule him out for the game.

"He has a back contusion, there was an X-ray that was clear here," Budenholzer told reporters after the game. "So we'll monitor him and see how he wakes up. See how he feels the rest of tonight and tomorrow."

Budenholzer would not be drawn on the outlook for Antetokounmpo for the rest of the series, but was buoyed by his ability to overcome wrist and knee injuries this season.

"We have to wait and see what the doctors say, most importantly what Giannis says," he said.

"We've been blessed with him being incredibly resilient and quick to heal. You've just got to take it day by day, see how he's doing and how he feels."

Budenholzer clarified that the decision to rule Antetokounmpo out of the game, after initially trying to play on, came given his limited mobility in the second quarter.

"He just wasn't moving [well]," Budenholzer said. "Didn't look comfortable or confident, so it felt like the right thing."

Bucks guard Jrue Holiday remained bullish about the Eastern Conference top seed's prospects in the series, even if MVP candidate Antetokounmpo is unavailable for any or all games.

"We don't want him to be hurt, but it's still next man up mentality," Holiday said. "We have enough talent on this team to cover for him until he comes back, so again, I just don't want to see him hurt because I know what it feels like, especially Game 1 of the playoffs."

Jimmy Butler top scored for the Heat, who overcame the first-half loss of Tyler Herro with a broken right hand.

Butler scored 35 points on 15-of-27 shooting along with 11 assists, while center Bam Adebayo had 22 points, nine rebounds and seven assists.

"He's just a brilliant competitor," Heat coach Erik Spoelstra said. "He does it on both ends of the court. He has an innate feel for what's necessary during the course of a game.

"We needed obviously some offensive punch, some triggers, something to settle us all down, particularly when we found out Tyler was out. Jimmy was able to do it in a lot of different ways."

Heat veteran Kevin Love hailed Butler as the best closer in the league.

"It's unbelievable what he's able to do out there," Love said. "He's our leader. He sets the tone for us. I'm taking him pretty much over anybody in the league when it comes down to closing out a game."